forked from antonblanchard/microwatt
-
Notifications
You must be signed in to change notification settings - Fork 0
/
control.vhdl
245 lines (204 loc) · 7.85 KB
/
control.vhdl
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
library ieee;
use ieee.std_logic_1164.all;
library work;
use work.common.all;
entity control is
generic (
PIPELINE_DEPTH : natural := 2
);
port (
clk : in std_ulogic;
rst : in std_ulogic;
complete_in : in std_ulogic;
valid_in : in std_ulogic;
flush_in : in std_ulogic;
stall_in : in std_ulogic;
sgl_pipe_in : in std_ulogic;
stop_mark_in : in std_ulogic;
gpr_write_valid_in : in std_ulogic;
gpr_write_in : in gspr_index_t;
gpr_bypassable : in std_ulogic;
gpr_a_read_valid_in : in std_ulogic;
gpr_a_read_in : in gspr_index_t;
gpr_b_read_valid_in : in std_ulogic;
gpr_b_read_in : in gspr_index_t;
gpr_c_read_valid_in : in std_ulogic;
gpr_c_read_in : in gpr_index_t;
cr_read_in : in std_ulogic;
cr_write_in : in std_ulogic;
valid_out : out std_ulogic;
stall_out : out std_ulogic;
stopped_out : out std_ulogic;
gpr_bypass_a : out std_ulogic;
gpr_bypass_b : out std_ulogic;
gpr_bypass_c : out std_ulogic
);
end entity control;
architecture rtl of control is
type state_type is (IDLE, WAIT_FOR_PREV_TO_COMPLETE, WAIT_FOR_CURR_TO_COMPLETE);
type reg_internal_type is record
state : state_type;
outstanding : integer range -1 to PIPELINE_DEPTH+2;
end record;
constant reg_internal_init : reg_internal_type := (state => IDLE, outstanding => 0);
signal r_int, rin_int : reg_internal_type := reg_internal_init;
signal stall_a_out : std_ulogic;
signal stall_b_out : std_ulogic;
signal stall_c_out : std_ulogic;
signal cr_stall_out : std_ulogic;
signal gpr_write_valid : std_ulogic := '0';
signal cr_write_valid : std_ulogic := '0';
signal gpr_c_read_in_fmt : std_ulogic_vector(5 downto 0);
begin
gpr_hazard0: entity work.gpr_hazard
generic map (
PIPELINE_DEPTH => PIPELINE_DEPTH
)
port map (
clk => clk,
stall_in => stall_in,
gpr_write_valid_in => gpr_write_valid,
gpr_write_in => gpr_write_in,
bypass_avail => gpr_bypassable,
gpr_read_valid_in => gpr_a_read_valid_in,
gpr_read_in => gpr_a_read_in,
stall_out => stall_a_out,
use_bypass => gpr_bypass_a
);
gpr_hazard1: entity work.gpr_hazard
generic map (
PIPELINE_DEPTH => PIPELINE_DEPTH
)
port map (
clk => clk,
stall_in => stall_in,
gpr_write_valid_in => gpr_write_valid,
gpr_write_in => gpr_write_in,
bypass_avail => gpr_bypassable,
gpr_read_valid_in => gpr_b_read_valid_in,
gpr_read_in => gpr_b_read_in,
stall_out => stall_b_out,
use_bypass => gpr_bypass_b
);
gpr_c_read_in_fmt <= "0" & gpr_c_read_in;
gpr_hazard2: entity work.gpr_hazard
generic map (
PIPELINE_DEPTH => PIPELINE_DEPTH
)
port map (
clk => clk,
stall_in => stall_in,
gpr_write_valid_in => gpr_write_valid,
gpr_write_in => gpr_write_in,
bypass_avail => gpr_bypassable,
gpr_read_valid_in => gpr_c_read_valid_in,
gpr_read_in => gpr_c_read_in_fmt,
stall_out => stall_c_out,
use_bypass => gpr_bypass_c
);
cr_hazard0: entity work.cr_hazard
generic map (
PIPELINE_DEPTH => PIPELINE_DEPTH
)
port map (
clk => clk,
stall_in => stall_in,
cr_read_in => cr_read_in,
cr_write_in => cr_write_valid,
stall_out => cr_stall_out
);
control0: process(clk)
begin
if rising_edge(clk) then
assert r_int.outstanding >= 0 and r_int.outstanding <= (PIPELINE_DEPTH+1) report "Outstanding bad " & integer'image(r_int.outstanding) severity failure;
r_int <= rin_int;
end if;
end process;
control1 : process(all)
variable v_int : reg_internal_type;
variable valid_tmp : std_ulogic;
variable stall_tmp : std_ulogic;
begin
v_int := r_int;
-- asynchronous
valid_tmp := valid_in and not flush_in and not stall_in;
stall_tmp := stall_in;
if complete_in = '1' then
v_int.outstanding := r_int.outstanding - 1;
end if;
if rst = '1' then
v_int.state := IDLE;
v_int.outstanding := 0;
stall_tmp := '0';
valid_tmp := '0';
end if;
-- Handle debugger stop
stopped_out <= '0';
if stop_mark_in = '1' and v_int.outstanding = 0 then
stopped_out <= '1';
end if;
-- state machine to handle instructions that must be single
-- through the pipeline.
case r_int.state is
when IDLE =>
if valid_tmp = '1' then
if (sgl_pipe_in = '1') then
if v_int.outstanding /= 0 then
v_int.state := WAIT_FOR_PREV_TO_COMPLETE;
stall_tmp := '1';
else
-- send insn out and wait on it to complete
v_int.state := WAIT_FOR_CURR_TO_COMPLETE;
end if;
else
-- let it go out if there are no GPR hazards
stall_tmp := stall_a_out or stall_b_out or stall_c_out or cr_stall_out;
end if;
end if;
when WAIT_FOR_PREV_TO_COMPLETE =>
if v_int.outstanding = 0 then
-- send insn out and wait on it to complete
v_int.state := WAIT_FOR_CURR_TO_COMPLETE;
else
stall_tmp := '1';
end if;
when WAIT_FOR_CURR_TO_COMPLETE =>
if v_int.outstanding = 0 then
v_int.state := IDLE;
-- XXX Don't replicate this
if valid_tmp = '1' then
if (sgl_pipe_in = '1') then
if v_int.outstanding /= 0 then
v_int.state := WAIT_FOR_PREV_TO_COMPLETE;
stall_tmp := '1';
else
-- send insn out and wait on it to complete
v_int.state := WAIT_FOR_CURR_TO_COMPLETE;
end if;
else
-- let it go out if there are no GPR hazards
stall_tmp := stall_a_out or stall_b_out or stall_c_out or cr_stall_out;
end if;
end if;
else
stall_tmp := '1';
end if;
end case;
if stall_tmp = '1' then
valid_tmp := '0';
end if;
if valid_tmp = '1' then
v_int.outstanding := v_int.outstanding + 1;
gpr_write_valid <= gpr_write_valid_in;
cr_write_valid <= cr_write_in;
else
gpr_write_valid <= '0';
cr_write_valid <= '0';
end if;
-- update outputs
valid_out <= valid_tmp;
stall_out <= stall_tmp;
-- update registers
rin_int <= v_int;
end process;
end;